JPH11261527A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate phase fluctuation of a received signal which is caused by a gain-phase characteristic of a receiving amplifier in real time. SOLUTION: The received signal amplified by a variable amplifying means 2 is inputted to mixers 3-1 and 3-2. A reference frequency signal LO from a local oscillator 4 is inputted to a delay block 5, undergoes phase shift as much quantity as to correspond to phase shift quantity acquired by referring to a gain-phase characteristic table of the means 2 and is outputted. The phase fluctuation of a received signal which is caused by a gain-phase characteristic of the means 2 is eliminated by such a manner that the mixers 3-1 and 3-2 perform orthogonal detection of an output of the means 2 by using the output signal LO'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiving apparatus for wireless communication using digital modulation, and more particularly, to a case of receiving a signal by a free-run receiver using a spread spectrum system or to equalize the phase of each antenna. It is suitable for use in a required array antenna receiving device.

[0002]

2. Description of the Related Art As a problem of wireless communication using digital modulation, there is a phase fluctuation of a demodulated baseband signal due to a gain-phase characteristic of a receiving amplifier of a receiver. For example, a spread-spectrum signal transmitted from a transmitting station is received while moving a receiver, and the I-phase and Q-phase correlation signal outputs and their envelope signals are observed to investigate radio wave propagation characteristics. Have been done. In such a case, the AGC (automatic gain control
oll: Automatic gain control), the gain of the amplifier-
Since the phase of the received signal fluctuates due to the phase characteristics, stable I-phase and Q-phase correlation outputs could not be obtained.
Therefore, real-time observation is not possible except for the envelope of the correlation signal. At the time of reception, the gain of the receiving amplifier is recorded together with the correlation output as preparation for offline processing, and the gain-phase characteristic of the AGC amplifier is recorded by offline processing. , It was necessary to correct the recorded correlation output.

FIG. 5 is a diagram showing a configuration example of a receiving apparatus in such a conventional spread spectrum system. In this figure, a received signal converted into a high-frequency signal or an intermediate frequency signal is input to a variable amplifier 2 and amplified to a predetermined power. Here, the gain of the variable amplifying means 2 is controlled by a gain control signal CNTL1 from the CPU 1 as a control unit. The output of the variable amplifying means 2 is supplied to the splitter 10-1.
, And input to the mixers 3-1 and 3-2. The local oscillator (local oscillator) 4 generates a reference frequency signal having the same frequency as the high-frequency signal or the intermediate frequency signal, and the reference frequency signal is supplied to the branching device 10-.
2, one of the outputs is directly input to the mixer 3-2, and the other output is phase-shifted by 90 ° by the π / 2 phase shifter 11, so that the mixer 3-2
1 is input.

In the mixers 3-1 and 3-2, the two-branch received signal output from the splitter 10-1 and the reference frequency signal from the local oscillator 4 and 90.degree. The phase-shifted reference frequency signals are respectively multiplied, and quadrature detection is performed. Outputs from the mixers 3-1 and 3-2 are input to correlators 9-1 and 9-2 via low-pass filters 8-1 and 8-2, respectively.
From I and 9-2, I-phase and Q-phase correlation signals I and Q are output. These correlation signals are stored in the storage device 13 and input to the envelope detector 12,
The absolute value, that is, the power of the correlation signal (√ (I ² + Q ² ))
Is detected, and the envelope signal is transmitted to the CPU as a control unit.
1 is input. The CPU 1 controls the gain control signal CNTL1 of the variable amplifying means 2 so that the input envelope signal has a constant value, and
1 as gain information in the storage device 13.
To memorize. After the measurement, the storage device 13
With reference to the gain-phase characteristic of the variable amplifying means 12 separately obtained based on the gain information stored in the above, a phase shift amount in the variable amplifying means 2 at each timing is obtained, and the phase shift amount is calculated using the phase shift amount. Correct correlation output is calculated by correcting the I-phase and Q-phase correlation signal outputs stored in the storage device 13.

[0005]

As described above, in the conventional receiver, real-time processing cannot be performed in order to obtain accurate phase information of a received signal. Therefore, data processing for offline processing must be performed. There was the inconvenience of not becoming. That is, in order to remove the influence of the gain-phase characteristic of the variable amplifying means, the corresponding gain information is stored in the storage device together with the I-phase and Q-phase correlation signal outputs, and the I-phase and Q-phase are stored by offline processing. It was necessary to correct the phase correlation signal output. In addition to the above-described observation of the propagation characteristics, the phase fluctuation caused by the gain-phase characteristics of the AGC becomes a serious problem even when an actual signal is received.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a receiving apparatus capable of canceling in real time the phase fluctuation of a demodulated baseband signal caused by the gain-phase characteristic of a receiving amplifier, which was impossible in the past. .

[0007]

To achieve the above object, a receiving apparatus according to the present invention comprises: a variable amplifying means for amplifying a received signal; a local oscillator for generating a reference frequency signal; And a demodulating means for demodulating a received signal output from the variable amplifying means using the variable amplifying means provided between the local oscillator and the demodulating means, wherein the phase of the reference frequency signal is adjusted by the variable amplifying means. Characterized in that a phase correction means for controlling the gain in accordance with the gain is provided. Further, the phase correction means uses a programmable phase shifter. This makes it possible to remove the phase fluctuation of the received signal caused by the gain-phase characteristic of the variable amplifier. Further, since the phase fluctuation is removed by controlling the phase of the reference frequency signal from the local oscillator, it is possible to perform processing in real time without delaying the received signal.

Further, referring to storage means for storing gain-phase characteristics of the variable amplifying means, and gain-phase characteristics stored in the storage means based on gain control information applied to the variable amplifying means. Control means for supplying a phase shift amount control signal to the phase correction means. This makes it possible to obtain the phase shift amount control information to be supplied to the phase correction means by referring to the gain-phase characteristics stored in the storage means.

Still further, there is provided means for inputting a signal having a known amplitude and phase to the variable amplifying means, obtaining gain-phase characteristics of the variable amplifying means from the output thereof, and storing the gain-phase characteristic in the storage means. It is. This makes it possible to acquire and store the gain-phase characteristic of the variable amplifying unit immediately before the measurement, and to perform more accurate phase correction.

Further, a correlator provided at a stage subsequent to the demodulation means, means for calculating an envelope of an output signal from the correlator, and a means for calculating the envelope signal so that the magnitude of the envelope signal is constant. Means for controlling the variable amplifying means so as to cancel the phase fluctuation of the correlation signal when receiving the spread spectrum signal. Thereby, in the receiver of the spread spectrum signal, AG
It is possible to provide a receiver of a spread spectrum signal capable of high-quality reception in which phase fluctuation caused by gain-phase characteristics of a C amplifier is removed.

Further, each array block is constituted by each antenna element of the array antenna and the receiving device provided in correspondence with each antenna element, and is caused by the gain-phase characteristic of the variable amplifying means. The arrangement is such that the phase fluctuation of the output signal of each array block is canceled. Thus, it is possible to provide an array antenna receiving apparatus capable of outputting a signal without phase fluctuation due to gain-phase characteristics from each antenna block.

[0012]

1 and 2 are block diagrams showing the configuration of an embodiment of a receiving apparatus according to the present invention. 1, the same components as those in FIG. 5 are denoted by the same reference numerals, and the description will not be repeated. In FIG. 1, reference numeral 5 denotes a delay block, which is provided between the local oscillator 4 and the splitter 10-2 as shown in FIG. 1, and receives a reference frequency signal LO from the local oscillator 4, As will be described later, a signal LO 'whose phase is shifted by an amount corresponding to the phase fluctuation in the variable amplifying means 2 is output to the branching device 10-2. Also,
In this embodiment, the received power and the gain-phase characteristic of the variable amplifying means 2 are input to the delay block 5, and the delay block 5 controls the variable amplifying means 2 to control the gain. The gain control signal CNTL1 is output.

FIG. 2 is a block diagram showing a configuration example of the delay block 5. As shown in FIG. In FIG. 1, reference numeral 1 denotes a CPU serving as a control unit; and 6, a gain-phase table in which gain-phase characteristic information of the variable amplifying unit 2 is stored. The gain-phase table 6 is stored in a storage unit. . Reference numeral 7 denotes an existing programmable signal which delays the phase of the reference frequency signal LO from the local oscillator 4 by an amount corresponding to the phase shift amount control information CNTL2 supplied from the control unit 1, and outputs the same as the signal LO '. -It is a phase shifter.

Here, as the gain-phase characteristic of the variable amplifying means 2 stored in the gain-phase table 6, characteristic data provided by a maker of the variable amplifying means 2 may be stored in advance. However, in this embodiment, a signal having a known phase and amplitude is input, and the gain of the variable amplifier 2 is controlled to increase or decrease the amplitude of the signal. Is calculated, and a shift of the correlation output with respect to the input signal phase is calculated using the control unit 1 or the like, and is written in the storage unit, thereby generating the gain-phase table 6. As a result, the gain-phase characteristic of the variable amplifying means 2 can be obtained immediately before the actual measurement, and a highly accurate operation excluding the influence of the temperature characteristic can be expected.

[0015] In the thus configured receiving apparatus,
As in the case described above, the received signal is amplified by the variable amplifying means 2, then branched by the splitter 10-1, and input to the mixers 3-1 and 3-2. On the other hand, the reference frequency signal LO from the local oscillator 4 is supplied by a programmable phase shifter 7 provided in the delay block 5 to an amount corresponding to the phase shift amount control information CNTL2 output from the control unit 1. And the output signal LO ′. This output signal LO 'is branched into two in a branching device 10-2, one output of which is input to the mixer 3-2, and the other output of which is input to the mixer 3-1 via a π / 2 phase shifter 11. Is done. The received signal output from the variable amplifying means 2 is
At -1 and 3-2, quadrature detection is performed using the output signal LO 'of the delay block 5 and output to the subsequent stage via low-pass filters 8-1 and 8-2.

In the delay block 5, the CPU 1 as a control unit monitors the power of the received signal and outputs a gain control signal CNTL1 to the variable amplifying means 2 so that the received signal power becomes a predetermined value. I do. CPU1
Refers to the gain-phase table 6 using the CNTL1 signal, and reads the amount of phase variation in the gain. Then, it generates the phase shift amount control information CNTL2 according to the phase fluctuation amount and outputs it to the programmable phase shifter 7. Programmable phase
The shifter 7 adjusts the phase delay amount of the reference frequency signal from the local oscillator 4 according to the phase shift amount control information CNTL2, and shifts the phase shift amount by the same amount as the phase fluctuation amount in the variable amplifying means 2. Signal LO '
Is output.

Thus, the splitter 10-2, π / 2
Mixers 3-1 and 3-2 through phase shifter 11
And the signals supplied from the splitter 10-1 to the mixers 3-1 and 3-2 are signals having the same amount of phase fluctuation, and the movement fluctuation in the quadrature detection output is canceled. It will be. Therefore, the phase fluctuation of the demodulated output caused by the gain-phase characteristic of the variable amplifying means 2 can be canceled. In addition, local
Since the phase fluctuation is canceled by controlling the phase of the reference frequency signal from the oscillator 4, no delay occurs in the received signal.

Next, an embodiment in which the receiving apparatus of the present invention is applied to a spread spectrum type receiving apparatus will be described. FIG. 3 is a block diagram showing a configuration example of an embodiment applied to a spread spectrum receiving apparatus. In this figure, the same components as those in FIG. 5 and FIG. 1 are denoted by the same reference numerals, and the description will be omitted. The delay block 5 in FIG. 3 has the same configuration as that shown in FIG.

In FIG. 3, the delay block 5 includes:
The envelope signal output from the envelope detector 12 is input as a received power signal, and the CPU 1
Monitors the envelope signal, and supplies the variable control means 2 with the gain control signal CNTL1 so that the value of the envelope signal becomes constant. The CPU 1 uses the information of the gain control signal CNTL1 to calculate the gain-
By referring to the phase table 6, the amount of phase fluctuation of the variable amplifying means 2 at the gain is obtained. Then, a phase shift amount control signal CNTL2 for canceling the phase fluctuation is supplied to the programmable phase shifter 7. Thus, as described above, quadrature detection is performed using the signal LO ′ in which the phase of the reference frequency signal LO is shifted by the same amount as the phase variation of the variable amplifying means 2, and the correlator 9-1 And 9-2 output in real time correlation signals I and Q which are not affected by the phase fluctuation. Thus, the correlation signals I and Q in FIG.
Are not affected by phase fluctuations caused by the gain-phase characteristic of the variable amplifying means 2.

Next, an embodiment in which the receiving apparatus of the present invention is applied to an array antenna will be described. FIG. 4 is a block diagram showing a configuration example of an embodiment in which the present invention is applied to an array antenna. In FIG. 4, the array antenna 1
4, phase fluctuation correction circuits 16 # 1 to 16 # n are connected to the antenna elements # 1 to #n, respectively.
An array block is composed of a phase fluctuation correction circuit corresponding to each antenna element. Here, each of the phase variation correction circuits 16 # 1 to 16 # n has the same configuration as that shown in FIG. 1 and FIG.

In such a configuration, the received signals input to each of the antenna elements # 1 to #n of the array antenna 14 are amplified to a signal of a sufficient level by the variable amplifying means 2 in the corresponding array block 15. However, as described above, the output signal I from each array block is
(1), I (2), ..., I (n), Q (1), Q
(2),..., Q (n) are not affected by the phase fluctuation caused by the gain-phase characteristic of the variable amplifying means 2,
The received signal can be sent to the subsequent processing unit.

[0022]

As described above, according to the present invention, in a radio communication receiving apparatus using digital modulation, it is possible to cancel the phase fluctuation caused by the gain-phase characteristic of the variable amplifying means. In addition, since the phase of the local oscillation signal is shifted instead of the received signal, phase correction can be performed without delay in processing of the received signal. Further, the variable amplification means 2
Of the gain-phase table 6
According to the invention of this application, the phase can be corrected using more accurate gain-phase characteristics.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of a receiving device according to an embodiment of the present invention;

FIG. 2 is a diagram showing a configuration example of a delay block 5 in the embodiment shown in FIG.

FIG. 3 is a diagram showing a configuration example of an embodiment in which the receiving device of the present invention is applied to a spread spectrum system.

FIG. 4 is a diagram illustrating a configuration example of an embodiment in which the receiving device of the present invention is applied to an array antenna receiving device.

FIG. 5 is a diagram illustrating a configuration example of a receiving apparatus in a conventional spread spectrum system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Variable amplification means 3-1 and 3-2 mixer 4 Local oscillator 5 Delay block 6 Gain-phase table 7 Programmable phase shifter 8-1, 8-2 LPF (low-pass filter) 9-1, 9 -2 Correlator 10-1, 10-2 Branching device 11 π / 2 shifter 12 Envelope detector 13 Storage device 14 Array antenna 15 Array block 16 # 1-16 # n Phase fluctuation correction circuit

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[Procedure amendment]

[Submission date] March 4, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction contents]

[0007]

To achieve the above object, a receiving apparatus according to the present invention comprises: a variable amplifying means for amplifying a received signal; a local oscillator for generating a reference frequency signal; A demodulating means for demodulating a received signal output from the variable amplifying means, wherein the gain of the variable amplifying means is provided between the local oscillator and the demodulating means.
Phase compensation means is provided for controlling the phase of the reference frequency signal in accordance with the gain of the variable amplifying means so as to compensate for the phase characteristics . Further, the phase correction means uses a programmable phase shifter. As a result, the gain of the variable amplifier
It is possible to remove the phase fluctuation of the received signal caused by the phase characteristic. Further, since the phase fluctuation is removed by controlling the phase of the reference frequency signal from the local oscillator, it is possible to perform processing in real time without delaying the received signal.

Claims (6)

[Claims] 1. A variable amplifying means for amplifying a received signal, a local oscillator for generating a reference frequency signal, and a demodulating means for demodulating a received signal output from the variable amplifying means using the reference frequency signal. A receiving device comprising: a phase correction unit provided between the local oscillator and the demodulation unit, the phase correction unit controlling a phase of the reference frequency signal according to a gain of the variable amplification unit. apparatus. 2. The apparatus according to claim 1, wherein
2. The receiving device according to claim 1, wherein the receiving device uses a phase shifter. 3. A storage means for storing gain-phase characteristics of the variable amplification means, and a gain-phase characteristic stored in the storage means based on gain control information applied to the variable amplification means. And a control means for supplying a phase shift amount control signal to said phase correction means.
The receiving device according to the above. 4. A means for inputting a signal having a known amplitude and a phase to the variable amplifying means, obtaining a gain-phase characteristic of the variable amplifying means from an output thereof, and storing the gain-phase characteristic in the storage means. The receiving device according to claim 3, characterized in that: 5. A correlator provided at a stage subsequent to said demodulation means, means for calculating an envelope of an output signal from said correlator, and said variable so that the magnitude of said envelope signal becomes a constant magnitude. Means for controlling the amplification means,
The receiver according to any one of claims 1 to 4, wherein a phase variation of the correlation signal at the time of receiving the spread spectrum signal is canceled. 6. Each array block is constituted by each antenna element of the array antenna and the receiving device according to any one of claims 1 to 4 provided corresponding to each antenna element. A receiving apparatus, wherein a phase variation of an output signal of each array block due to a gain-phase characteristic of a variable amplifying means is canceled.